Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 292342 RRA AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 741 PM EDT MON AUG 29 2016 .SYNOPSIS... An ENE to NE onshore flow will prevail through mid-week as Tropical Depression 8 approaches the Carolina coast from the ESE and high pressure shifts slowly east from the lower Great Lakes to the Mid- Atlantic coast. && .NEAR TERM /THROUGH TONIGHT/... As of 135 PM Monday... A dry low/mid-level airmass persists over the majority of central NC this morning, as sampled by the 12Z GSO RAOB (PWAT 1.11") and indicated by the latest 925/850 mb SPC mesoanalysis. Moisture increases rapidly as one progresses east of the I-95 corridor in the Coastal Plain where NE low-level flow has advected rich low-level moisture from the Atlantic into Eastern NC, as indicated by the 12Z MHX RAOB (PWAT 1.83"). Marginal destabilization (tempered by cloud cover and NE low-level flow) will be confined to areas along/east of I-95 this afternoon. Forcing for ascent will also be confined to areas along/east of I-95, in the form of weak DPVA assoc/w a shear axis extending N/NNE along the Southeast/Carolina coast, attendant a stalled upper level low offshore the GA/FL coast. With the above in mind, expect mostly cloudy skies and a slight chance of showers to along/east of the I-95 corridor this aft/eve, with partly cloudy skies and dry conditions elsewhere. Expect highs in the mid/upper 80s, coolest east of I-95. Lows tonight will range from the upper 60s (western and northern Piedmont) to lower 70s in the Coastal Plain, primarily east of I-95. -Vincent && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... As of 135 PM Monday... Moisture will increase over central NC on Tuesday as an E/NE onshore flow expands westward across the state, with PWAT values rising in comparison to today as , the shear axis extending N/NNW into the area (from a stalled upper level low offshore the GA/FL coast) today is expected to shift W/SW into western NC, upstate SC and northern GA. As a result, forcing will largely be absent Tue/Tue night. In fact, subsidence is likely to be present over portions of central/ eastern NC on the western periphery of TD #8 Tue aft/eve (progged to be a marginal tropical storm by then) as it approaches the NC OBX. With the above in mind, will indicate a dry forecast over central NC Tue/Tue night, with the best chance for precip along the Carolina/ Southeast coast. Expect partly cloudy skies with highs in the upper 80s to near 90F. Lows Wed in the upper 60s to lower 70s. -Vincent && .LONG TERM /WEDNESDAY THROUGH MONDAY/... As of 300 PM Wednesday... Lots of interesting weather features to watch for during the mid to late week period. Wednesday: The approach of a northern stream shortwave trough diving se through the Great Lakes and Ohio River valley on Wednesday will erode the weakening ridge in place and cause T.D. 8 to recurve northeastward and away from the NC coast. Meanwhile, nearly all models indicate some weak sfc cyclogenesis along a weak coastal trough and in proximity to the weakening mid-level circulation/trough along the GA/SC coast. This feature too will feel the influence of the approaching northern stream trough, and is expected to quickly skirt ne away from the NC coast late Wednesday/Wednesday night. Thus with no forcing mechanisms, central NC will continue to see a continuation of mostly dry conditions with temps in the upper 80s to lower 90s. Thursday-Thursday night: Aforementioned northern stream trough and attendant cold front will progress southeast into the region Thursday afternoon/evening. Once again, this northern stream trough will impact the tropics, with attendant belt of westerlies picking up what is now T.D. 9 and inducing a north-northeastward acceleration across northern Florida and up along the Southeast Coast late Thursday night and Friday. Will have to monitor how the track and timing evolves over the next couple of days, but if everything lines up, it`s possible that convection along the front could increase in both intensity and coverage Thursday afternoon and Thursday night(possible PRE??),as it intercepts the tropical moisture plume advecting poleward into the area. For now will continue to feature a NW-SE pop gradient, highest pops se. Temps will continue to remain above normal until the front moves through. Friday through Monday: Official NHC track of T.D. 9 moves it off the Southeast and Mid-Atlantic Coast Friday-Friday night. Could see some lingering showers in the east early Friday, otherwise it will be dry with cooler temps as Canadian high pressure builds south in the area. Highs over the weekend in the lower 80s north to mid 80s south. Lows in the lower to mid 60s. Temperatures should start to rebound early next week as upper ridging build back over the region. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/...
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As of 741 PM Monday... 24-hr TAF Period through 31/0000z: Mainly VFR conditions are expected during this time as dry air persists over most of central NC. The dry air exception will be south and east of the Triangle where NE winds are promoting a moist flow off the Atlantic. As such, our eastern zones and sites including KRWI and KFAY, may see a brief period of MVFR stratus toward daybreak Tuesday, however outside of that, expect mostly VFR conditions and NE winds less than 10kt during this period. Looking ahead: Forecast confidence decreases mid-week due to uncertainty assoc/w the evolution of TD #8 offshore the Carolina coast and an upper level low offshore the Southeast coast. Forecast confidence remains low late this week into this weekend when a cold front approaching from the NW is progged to interact with TD #9 (located west of the FL Keys in the GOMEX this morning) as it tracks NE across northern FL and emerges offshore the Southeast coast. With the above in mind, VFR conditions are most likely to prevail at western terminals (INT/GSO), and eastern terminals (FAY/RWI) are most likely to see periodic showers and low ceilings mid/late week. -Vincent
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&& .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Vincent NEAR TERM...Vincent SHORT TERM...Vincent LONG TERM...CBL is the U.S. government's official web portal to all federal, state and local government web resources and services.